Automotive designers have increasingly turned to impact-responsive devices to protect occupants against the effects of an impact event directed against a vehicle. Responsive devices first included such mechanisms as inertia responsive seatbelt reels, and later, inflatable side curtain airbags to supplement airbags mounted within the instrument panel and steering wheel. In the event of an impact directed against an upper surface of a vehicle such as the vehicle's top, or in the case of a pedestrian accident, the vehicle's hood, it is desirable to provide additional strength to these panels. In the case of the vehicle top, additional strength will assist in mitigating crushing of the top; in the case of an engine compartment hood, additional strength will mitigate strikethrough of the hood to the much more rigid engine of the vehicle.
The present invention provides structures which may be employed to selectively increase the strength of a vehicle's top or engine compartment hood, or other panels, in the event of an impact event directed against a vehicle.